Working surface cleaning system and method

ABSTRACT

A cleaning film designed to remove foreign matter and particulates from working surfaces of cleaning wafers used in semiconductor processes. These processes include wafer sort test for cleaning of probe card pins and FEOL tooling for cleaning during wafer handling equipment and wafer chucks. The debris collected on the cleaning wafer working surfaces is removed by the particle removal film allowing the debris and foreign matter to be discarded. The use of the cleaning film allows the operator to refresh the cleaning wafer without use of an outside vendor and eliminates wet washing and the use of solvents in the cleaning process.

PRIORITY CLAIMS/RELATED APPLICATIONS

This application is a continuation in part of and claims priority under35 USC 120 to U.S. patent application Ser. No. 13/912,840, filed Jun. 7,2013 and titled “Working Surface Cleaning System And Method” which is inturn a continuation of and claims priority under 35 USC 120 to U.S.patent application Ser. No. 11/237,596, filed on Sep. 27, 2005 andentitled “Cleaning Method” which in turn claims the benefit under 35 USC119(e) to U.S. Provisional patent application Ser. No. 60/614,073 filedof Sep. 28, 2004, the entirety of both of which are incorporated hereinby reference.

FIELD

The disclosure relates generally to a material, device, and method forremoving particles and other foreign matter from the working surface ofa cleaning device which is used during semiconductor manufacturing andtesting.

BACKGROUND

It is desirable to be able to clean the working surface of devices thatare used for probe card cleaning and semiconductor hardware cleaningwafers which are used to remove debris from wafer handling equipment(such as robot arms and end effectors) and wafer stages (such as a waferchuck, wafer tables and/or pre-align chucks). The foreign matter andparticulates collected on the probe card cleaning and hardware cleaningwafers are removed by the particle removal device that allows thesurface debris that has been collected and removed from a probe card orthe wafer handling hardware to be collected and discarded.

It is desirable to provide a cleaning method that allows the use of theparticle removal device to refresh the working surface without the useof an outside vendor or the use of a wet washing step as part of thecleaning process.

Thus, it is desirable to provide such as cleaning method and system andit is to this end that the disclosure is directed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a cleaning film polymer with protectiveliner and film backing;

FIG. 2 is a flow chart showing process steps for the cleaning film asused in on-probe cleaning wafers or chuck cleaning wafers; and

FIGS. 3A-3D are photographic representations of the application andremoval of the cleaning film.

DETAILED DESCRIPTION OF ONE OR MORE EMBODIMENTS

The disclosure is directed to a device, material, and method designed tonon-destructively and non-invasively remove foreign matter andparticulates from the working surfaces of cleaning devices that are usedfor probe card cleaning during semiconductor device testing. Thecleaning device and method can also be used to remove foreign matter andparticulates from the working surfaces of cleaning devices and wafersused for cleaning wafer handling hardware and wafer stages in front endof line (FEOL) equipment during semiconductor device manufacturing.

The probe card cleaning materials as described in prior art can consistof unfilled and particulate filled elastomers to provide abrasiveproperties for debris removal and surface tack properties to collect thedislodged debris.

Debris is removed from the wafer test probe pins through contact withprobe card cleaning materials. After repeated use of the probe cardcleaning material, dislodged debris accumulates on the cleaning deviceworking surface reducing contact with the probes to be cleaned andtherefore diminishing the effectiveness of the material. The priormethod for removing the accumulated debris consisted of a wet washingprocess to remove foreign matter and particulates from the cleaningmaterial working surface with a solvent such as isopropyl alcohol.

The particle removal device and method extends to cleaning and debriscollection from the cleaning wafers that are used in other front end ofline (FEOL) processes such as stepper, photolithography, PVD, CVD andEtch tools. In the case of cleaning devices and wafers that are used toremove foreign matter and particulates from wafer handling hardware andwafer chucks in front end of line (FEOL) semiconductor devicemanufacturing tools, debris during the cleaning process will accumulateon the working surface of the cleaning device or wafer. Once particlesand contaminants are collected and removed from the FEOL semiconductormanufacturing tool by the cleaning wafer it should not be recycledthrough the FEOL tool without a surface cleaning due to the risk of thecollected debris re-entering the tool. For example, the FEOL cleaningwafer is used to remove particulate causing de-focus spots inlithography tools and as the particle is removed from the tool thechance of the particle causing a de-focus re-occurrence is eliminated.The particle must not re-enter the tool on the cleaning wafer. Theparticle removal device is used to lift the debris from the FEOLcleaning wafer surface and after usage, the particle removal device issubsequently discarded. Similar to probe cleaning wafers, the priormethod for removing the accumulated debris consisted of wet washing thecleaning material surface with a solvent such as isopropyl alcohol.

The disclosure is directed to a non-destructive, solvent free method ofeffectively removing collected debris on the cleaning material surface.The device and method effectively extends the lifetime of the cleaningmaterial surface while retaining the surface tack and abrasiveproperties required for proper cleaning of probe card pins and waferchucks.

Referring now to the device in more detail, in FIG. 1 there is shown acleaning polymer, or particle removal film, 10 affixed to a plastic filmbacking composed of one or more intermediate layers 30 and protected bycontact with a release surface coated liner film 20. In FIG. 1, theplastic film backing 20 is made of one or more intermediate layers ofpolyethylene terephthalate (PET) or other material that allowsapplication of the cleaning polymer during manufacturing and also allowsflexing or bending during application to and removal from the cleaningmaterial surface. The removable protective layer 20 that is installedprior to the intended usage for contact element cleaning in order toisolate the surface cleaning pad layer from non-test relatedcontaminants. The removable protective layer 20 protects the workingsurface of the cleaning pad layer 202 from debris/contaminants until thecleaning device is ready to be used for cleaning a tester interface in aclean room. When the cleaning device is ready to be used for cleaning atester interface in a clean room, the removable protective layer 20 maybe removed to expose the working surface of the cleaning pad layer 10.The protective layer may be made of a known non-reactive polymeric filmmaterial and preferably made of a polyester (PET) film. The protectivelayer may have a matte finish or other “textured” features to improvethe optical detection of the cleaning device by the testing equipmentand/or improve cleaning efficiency.

Additional intermediate materials layers with predetermined propertiescan be used for the plastic film backing to support the cleaning polymerlayer, or particle removal layer. The cleaning polymer layer 10 iscomprised of an elastic polymer, such as acrylic polymer, a butadieneelastomer, a styrene copolymer elastomer, a silicone elastomer or otherpolymer with adhesive properties, with a controlled surface tack, orsurface adhesion, and does not transfer materials. The elastic, adhesivepolymer is formed on the surface of the plastic backing to produce acontinuous, flexible, flat film. The polymer material is preferably anacrylic elastomer but may be silicone, rubber based or any other elasticpolymer that can be formed with a surface tack property between 8.0 and50.0 psi. The elastic polymer material is processed to be durable underrepeated handling without a reduction in surface tack or surfaceadhesion. The material should be sufficiently processed and/orcross-linked such that transference from the particle removal film tothe cleaning material surface does not occur. The thickness of theparticle removal polymer layer is preferably 0.0005 inches to 0.010inches. The thickness of the polymer is sufficient to allow the materialto deform around the particulate on the cleaning material surface tocollect debris that has accumulated during contact of the probe cardpins on the cleaning material surface. A protective release film layeror liner 30 is shown which will consist of a plastic film such aspolyethylene terephthalate (PET) or similar plastic material where a lowsurface energy coating such as silicone or fluorosilicone has beenapplied to allow easy removal of the protective liner from the cleaningpolymer layer without transfer of material.

The one or more intermediate layers 30 (that may also be one to Ncompliant support layers) may be attached to and below the cleaning padlayer 10. The combinations of layers in the one or more intermediatelayers 30 produce material properties unavailable from the individualconstituent materials, while the wide variety of matrix, abrasiveparticles, and geometries allows for a product or structure that has tochoose an optimum combination to maximize cleaning performance. Byadding compliant or microporous foam underlayers beneath a rigidcleaning layer, the overall abrasive wear characteristics of thecleaning material are reduced and/or the tip shaping performance areenhanced in order to extend the overall service life of the probeelement without compromising the shape or function of the contactgeometry. For example, application of the abrasive particle layer onto arigid polyester film creates a lapping film type cleaning material withstock removal characteristics used to create and maintain a probecontact elements with flat contact area geometries. Application of thesame abrasive particle layer to the surface of a compliant unfilledpolymer or the “skin” side of a microporous foam, results inmulti-layered material with preferential stock removal characteristicsfor creating and maintaining a probe contact element with a radius orsemi-radius contact area geometry. As the overall compliance of theunderlayer(s) is systematically increased (or rigidity is decreased),the overall abrasive wear characteristics of the cleaning materialtransition from creating and maintaining a flat tip contact areageometry to creating and maintaining a radius or semi-radius contactarea geometry.

The one or more intermediate layers (which can be compliant as describedabove, rigid as described below or a combination of compliant and rigidlayers as described below) may provide predetermined mechanical,material, and dimensional characteristics to the cleaning material. Forexample, the one or more intermediate layers may provide abrasiveness(described in more detail below), a specific gravity (of a range of 0.75to 2.27 for example) wherein specific gravity is the ratio of thedensity of the one or more intermediate layers to the density of waterat a particular temperature, elasticity (of a range of 40-MPa to 600-MPafor example), tackiness (of a range of 20 to 800 grams for example),planarity, thickness (a range between 25-um and 300-um for example),and/or a hardness between 30 Shore A and 90 Shore A.

Referring to FIG. 2, a flow chart is shown outlining a method 100 to usethe particle removal film to remove debris from a used probe cleaningwafer or chuck cleaning wafer. In FIG. 2, a probe card cleaning wafer ora FEOL tool cleaning wafer that was used to remove debris is taken outof service (i.e. removed from the prober or lithography tool) and placedon a vacuum chuck to secure the wafer in place (102). The particleremoval film protective liner is removed (104) and, preferablyconcurrently, the particle removal film layer is laminated to theworking surface of the cleaning wafer. The debris or foreign matter thathas been collected on the cleaning wafer working surface through normalprocessing now is preferentially adhered to the cleaning film surface.Particulate debris and foreign matter gets attached to the particleremoval film surface due to the greater magnitude of surface tack andadhesion force of the particle removal polymer materials. The surfacetack and adhesion properties of the particle removal film surface arepredetermined to range from 40 to 1600 grams such that they exceed thesurface tack and adhesion properties of the cleaning polymer, which canrange from 20 to 800 grams, for example. The tack or surface adhesionlevel of the particle removal film surface is up to 50 psi or greaterthan that of the cleaning polymer and, therefore, substantially greaterthan that of the working surface of the cleaning polymer. As shown inFIG. 2, the cleaning film also may be applied to the wafer surface witha manual roller.

FIGS. 3A-3D show photographic representations of the use of the particleremoval film to clean the surface of a cleaning wafer typically used forprobe card cleaning or for debris removal from FEOL tools. In FIG. 3A,the cleaning wafer 40 is placed on a vacuum chuck 50 to secure the waferfor application of the particle removal film. A protective liner of theremoval film shown in FIG. 1 is removed 60 as the particle removal filmpolymer 70 is applied to the working surface of the cleaning wafer asshown in FIG. 3B. Debris from the working surface preferentially adheresto the particle removal film once full contact is achieved with thewafer surface as shown in FIG. 3C. As the cleaning film is removed 80 asshown in FIG. 3D, the debris is lifted from the cleaning wafer surfaceand discarded with the film.

Upon removal of the cleaning film, the trapped particulate debris andforeign matter is lifted from the cleaning wafer surface (106) andproperly discarded along with the cleaning film (108). In one case, theremoval of the cleaning film from the cleaning wafer surface isfacilitated by the difference in surface energy level as the surfaceenergy of the cleaning wafer is approximately 10 to 30 dyne/cm and thecleaning film polymer surface energy is approximately 40 to 60 dyne/cm.This difference prohibits adhesion and physical contact (i.e. surfacewetting) between the materials and allows easy manual removal of theparticle removal film. After removal of the particles from the workingsurface, the particle removal film is discarded along with the collecteddebris and foreign matter. The working surface of the cleaning wafer isnow free of loose debris and can be returned to service cleaning probecard pins or semiconductor fabrication process chucks.

In one embodiment, the device cleans the working surface of asemiconductor process cleaning wafer (i.e. probe card cleaning orlithography wafer chuck cleaning). The device collects debris andforeign matter that has accumulated on the working surface of thecleaning wafer during normal usage. The debris preferentially adheres tothe cleaning device allowing removal and discard. The device allowscleaning and refreshing of the cleaning wafer working surface withoutrequiring the shipment of the wafer for refurbishing at an outsidevendor. The device also eliminates the use of wet washing and the use ofsolvents from the wafer cleaning process.

In the method, a piece of semiconductor processing equipment (such asthe probe card device or FEOL devices described above) may use acleaning wafer the clean the piece of semiconductor processingequipment, such as the probes of a probe card. Following a plurality ofcleanings, when the cleaning wafer has debris on it, the cleaning waferis removed from the piece of semiconductor processing equipment and thencleaned as described above. Once the cleaning wafer is cleaned using thecleaning film, the cleaning wafer is returned to service in the piece ofsemiconductor processing equipment to be used to clean the piece ofsemiconductor processing equipment.

While the foregoing written description of the invention enables one ofordinary skill to make and use what is considered presently to be thebest mode thereof, those of ordinary skill will understand andappreciate the existence of variations, combinations, and equivalents ofthe specific embodiment, method, and examples herein. The inventionshould therefore not be limited by the above described embodiment,methods, and examples, but by all embodiments and methods within thescope and spirit of the invention as claimed.

The invention claimed is:
 1. A method for cleaning a cleaning wafer thatis used to clean one of a probe card cleaning wafer and a FEOL toolcleaning wafer, the method comprising: securing a cleaning wafer havinga cleaning polymer, the cleaning polymer having debris embedded in a topsurface of the cleaning polymer; and applying a cleaning film to the topsurface of the cleaning polymer of the cleaning wafer to remove debrisfrom the top surface of the cleaning polymer of the cleaning wafer; andwherein a difference in one of surface tack and adhesion force betweenthe cleaning film and the cleaning polymer of the cleaning wafer causesthe debris to release from the top surface of the cleaning polymer ofthe cleaning wafer onto the cleaning film without using a solvent. 2.The method of claim 1, wherein securing the cleaning wafer furthercomprises placing the cleaning wafer on a vacuum chuck.
 3. The method ofclaim 1, wherein applying the cleaning film further comprises removing aprotective liner that covers a cleaning polymer layer of the cleaningfilm before applying the cleaning film to the top surface of thecleaning polymer of the cleaning wafer.
 4. The method of claim 1,wherein applying the cleaning film further comprises using a manualroller to apply the cleaning film to the top surface of the cleaningpolymer of the cleaning wafer.
 5. The method of claim 1 furthercomprising discarding the cleaning film with the embedded debris.
 6. Themethod of claim 5 further comprising returning the cleaning wafer toservice after it has been cleaned using the cleaning film.
 7. The methodof claim 5, wherein returning to cleaning wafer to service furthercomprising installing the cleaning wafer back into a front end of theline piece of equipment.
 8. The method of claim 5, wherein returning tocleaning wafer to service further comprising installing the cleaningwafer back into a probe card machine.